I am uncertain even as an electrician as to type of RCD, there is a logo on the RCD/RBCO like this
which in this case shows it is type A with just wavy line without bumpy line under it is type AC seems many this is the only marking to show which type. It is reported there is a potential problem with type AC that if diode fail on power supplies it can raise the tripping current to above the rated 30 mA so with inverter drives and switch mode power supplies one should use type AC or better, but there are also reports to say in practice on testing there were no faults found, however some countries have banned the use of type AC.
As to "Should I get surge protection and/or arc fault protection." again I really don't know, maybe with aerial feeds the surge protection is good, I fitted it to my house as it came with the board, as to arc fault protection with a wood frame house I would say again maybe, but we have had electrical supplies for years without them, and no real problems. I note they are on the best practice guide as items to check for with an electrical installation condition report, but with my brick built house I would not worry too much. It is a risk assessment with arc fault protection and also how many RCD's, unlike the MCB and surge protection which never tends to trip in error an AFDD or RCD can trip in error, this can plunge you into darkness, or cause the loss of a freezer full of food, so having a board of RCBO's instead of two RCD's means they are less likely to trip in error, and if they do trip only one circuit is affected. It also means the board is shorter, as RCD's take up two slots each. But my all RCBO's board cost over £200 for 14 way, and that was cheap, I miss read the spec and got type AC RCBO's instead of type A likely with type A a 14 way board will cost over £250 before the fitting, however if you look at the cost of a freezer full of food, that is not that expensive, last house we had to dump two freezers full of food as the RCD tripped when we were away, modern freezers well at least mine on power returning shows how warm it got, so even if power lost and restored without your knowledge it shows what the highest temperature was. However I have not found anything to say food needs dumping if it reaches x°C at any time, and unlike bringing food home in the car it takes some time for temperature to both rise and fall inside a freezer, so if it shows -1°C so still frozen question is how long it has been at -1°C?
The other point is with a genuine trip, how do you keep the freezer powered while you find the cause? To plug in to the cooker supply, or even run an extension lead to other side of the house will keep things running with reasonable safety until fault is found, however running an extension lead up/down the stairs is clearly a hazard specially with no lights, so if sockets split side/side or front/back then two RCD's can be used and there is a safe way to in an emergency get power to a freezer, but up/down often there is no safe method. The idea is lights in any one room should not be powered by same RCD as sockets in that room, so if there is an accident which trips sockets your not also plunged into darkness, if as with this house sockets split front/back and lights split up/down then this can't be arranged with just two RCD's.
The regulations do not say use two RCD's, as clearly with emergency lights there is no danger, and if your prepared to dump a freezer full of food then no risk, and we are told one should test the leakage, seem to remember 9 mA is the limit for all circuits on a 30 mA RCD which can trip between 15 mA and 30 mA, so if the electrician actually measures first then a RCD should not trip without reason, but read this forum and clearly they do.
So you assess the risk, if you feel you want to pay extra and have all RCBO protection, or some RCBO protection with a board with three neutral bars that is up to you, the electrician may say the back ground leakage is too high, you need more than two RCD's but in the main they offer the cheapest option, which may not be the best option, and if the board uses RCBO's at £26 each instead of £16 that can result in a rather expensive board, it is all well and good saying I like MK consumer units, but the metal consumer units have only been made in any quantity for some 3 years or so, so really no one has had time to find fault with certain makes of consumer unit, OK some may be harder to wire, but as user that does not really matter to you, so may as well open the book blind folded and stick in a pin.
